Draw blood in a plain red-top tube. Centrifuge, separate serum from cells within 2 hours of collection and send 1.0 mL serum (0.6 mL minimum) refrigerated in a screw-capped plastic vial. Sample should be collected between 15 weeks 0 days and 22 weeks 6 days gestation. Completed Prenatal Screen Information Sheet located (above) under Test Documentation and in the Appendices of the Test Directory, must accompany sample.